520 Work Begins in Arboretum

Workers pouring gravel on the WSDOT Peninsula in the Arboretum to create a stating area for construction of the WABN.

Construction of the West Approach Bridge North (WABN) phase of the new State Route 520 Bridge in the Arboretum has begun. This project will connect westbound-traveling vehicles, transit, bicycles, and pedestrians from the new floating bridge across Lake Washington to the Montlake area. Eastbound traffic will continue to use the existing structure until the West Approach Bridge South is fully funded and built.

In late September, workers from the Washington State Department of Transportation (WSDOT) closed off the Miller Street parking lot at the northern tip of the Arboretum to public use. They will be using a large portion of the WSDOT Peninsula adjacent to this parking lot as a staging area for the bridge construction.

Included in the WABN phase of the 520 rebuild will be the demolition of the former Museum of History and Industry building, the “ramps to nowhere” in the Arboretum, and the existing westbound off ramp that runs through the Arboretum wetlands and empties out onto Lake Washington Boulevard.

Workers have installed orange construction fencing around the project boundaries, and will mark temporary access restrictions to the Arboretum shoreline and trails. During the staging and bridge construction, some trees will need to be taken down, but WSDOT says it will work closely with the City of Seattle to minimize tree removal and ensure protection of the remaining vegetation.

According to WSDOT’s construction notice, “Crews will only remove trees and vegetation within the project’s limits as necessary to allow room to build the new structure, including on Foster Island. After construction is complete, the area will be replanted to create a well-blended and integrated landscape.”

The new approach bridge is scheduled to open to traffic in summer 2017.